This woman hadn't been drinking. So why did she have so much alcohol in her urine?

A 61-year-old woman who needed a liver transplant was disqualified from getting one because her urine kept testing positive for alcohol. But when the woman insisted she hadn't been drinking, her doctors didn't believe her—until one group of researchers made an important discovery, according to a case study published Tuesday in the Annals of Internal Medicine.

What follow-up tests revealed

The patient came to the University of Pittsburgh Medical Center (UPMC) Presbyterian Hospital with cirrhosis of the liver and diabetes. Her cirrhosis was so severe that she was placed on the liver transplant waitlist, the researchers said.

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According to the case study, the woman had previously visited another hospital but was denied a spot on the liver-transplant waitlist because her urine kept testing positive for alcohol. The woman insisted she hadn't been drinking, but her doctors believed she was lying to cover up an alcohol addiction. Instead of putting her on the transplant list, they enrolled the woman in an alcohol misuse treatment program.

The authors of the study, a group of researchers at UPMC, said their initial interactions with the patient "were similar." Even though the woman denied drinking alcohol, her urine kept testing positive for ethanol, "leading [the] clinicians to believe that she was hiding an alcohol use disorder," they wrote.

But there were some signs that the case was more complicated than they originally thought.

For one, even though the patient's urine had a high alcohol concentration, she showed no signs of intoxication.

In addition, when the doctors drew the woman's blood and tested her plasma, they didn't find any traces of ethanol. They also tested her urine for ethyl sulfate and ethyl glucuronide, chemicals the body produces to metabolize alcohol, but neither of the chemicals showed up in the lab tests.

What did show up in her urine test was a large amount of sugar and yeast, which both contribute to fermentation, according to report co-author Kenichi Tamama, an associate professor of pathology and medical director of UPMC's Clinical Toxicology Laboratory.

"As I went over the medical record of the patient and learned the situation of the patient, I started feeling obliged to do something for this patient, because she might have been falsely mislabeled as an alcohol abuser," Tamama said.

Tamama and the researchers decided to perform one more test. The researchers incubated one of the patient's fresh urine samples in the lab and found the samples became more alcoholic after they were left to ferment. The doctors realized that a similar fermentation process may be happening in the woman's body.

According to doctors, the yeast inside the patient's body was fermenting sugar in her bladder, which explained the ethanol showing up in her urine tests.

Once doctors made the diagnosis, the woman was "reconsidered for liver transplantation," the researchers wrote. According to the Washington Post, it's not clear whether she will receive one.

Can the body can become a brewery?

The woman's condition could be a new form of auto-brewery syndrome (ABS), the researchers said. ABS is a condition in which microbes in the gastrointestinal tract convert carbs into alcohol. In this woman's case, fermentation was occurring in the bladder.

Some people with ABS can get drunk after eating carbs, but because the alcohol couldn't travel from the woman's bladder to her bloodstream, the woman never seemed intoxicated.

While there have been other reported cases of ABS, some researchers have disputed whether the condition exists, according to the Post. A review published in 2000 found that "to date none of the studies published supporting the theory have withstood close scrutiny."

However, since the review, multiple case studies have documented suspected cases of the condition, the Post reports. In one case, a 46-year-old man who was pulled over on suspicion that he'd been driving drunk said he had the condition. At the hospital, his blood alcohol level was more than twice the legal limit, but a study published last year confirmed that fungi in the man's gut were brewing alcohol, making him seem intoxicated. One study published in 2019 said that ABS is likely an "underdiagnosed medical condition."

The authors of the case study hope the new report will highlight "the importance of recognizing urinary auto-brewery syndrome when it is present" (Shepherd, Washington Post, 2/24; Rettner, LiveScience, 2/24; Norton, HealthDay, 2/24).

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